1. Technical Field
Embodiments of the present invention generally relate to an electrical plug connector. More particularly, embodiments of the present invention relate to an electrical plug connector with retractable prongs.
2. Discussion of the Related Art
Electrical devices typically utilize an electrical plug connector in order to receive power from an electrical wall outlet or other power source. Electrical devices are often stored when not in use and/or during transfer from one place to another, and corresponding electrical plug connectors are generally stored with the electrical devices to enable use of the electrical devices upon reaching a destination. For example, many students and business persons carry personal computers in cases while traveling to and from classes or work. In another example, air travelers may pack electrical devices such as curling irons and electric shavers in their luggage. Because the prongs of an electrical plug connector protrude from its outer body, electrical plug connectors with fixed prongs are typically awkward in shape and may occupy a significant amount of space when stored in a confined area, such as a computer bag or a piece of carry-on luggage. Moreover, the prongs of an electrical plug connector generally have sharp edges that may pose a safety hazard.
To overcome these problems, several folding electrical plug connectors with retractable or removable prongs have been designed. One approach, disclosed in U.S. Pat. No. D454,537 (“the '537 Patent”), employs an interchangeable plug fitting that may be slidably detached from within a cavity formed in a main body. However, the interchangeable plug fitting may be misplaced after it is detached from the main body, especially if the interchangeable plug fitting is detached prior to transit. Furthermore, detaching the interchangeable plug fitting generally increases the storage space required to store the electrical plug connector.
According to another approach, disclosed generally in U.S. Pat. No. 6,312,271 (“the '271 Patent”), U.S. Pat. No. 5,401,178 (“the '178 Patent”), U.S. Pat. No. 6,089,886 (“the '886 Patent”), and U.S. Pat. No. 5,494,449 (“the '449 Patent”), a foldable electrical plug connector includes two retractable prongs. The two prongs are connected by a common rod about which the prongs are rotated from a first position, in which the prongs extend outward from a first face, to a second position in which the prongs fit into a groove within a connector housing. The prongs may be held in a retracted state by an orienting base (in the '271 Patent), a spring force (in the '178 Patent), notches (in the '886 Patent), or a tongue (in the '449 Patent).
U.S. Pat. No. 5,613,863 (“the '863 Patent”), U.S. Pat. No. 4,467,263 (“the '263 Patent”), U.S. Pat. No. 4,075,458 (“the '458 Patent”), and 3,027,507 (“the '507 Patent”) disclose various electrical devices that utilize a retractable two-prong plug. However, none of these patents disclose a retractable plug suitable for use with three prong outlets of the type commonly used throughout Europe. Furthermore, these plugs do not provide the user with a simple way to change the foldable electrical plug connector from the retracted state to the extended state.
U.S. Pat. No. 6,126,460 (“the '460 Patent”), U.S. Pat. No. 5,967,807 (“the '807 Patent”), and U.S. Pat. No. 4,997,381 (“the '381 Patent”) describe a dual-use plug with two sets of two prongs. A primary plug may be retracted as a unit into a cavity in a power supply housing and the prongs of a secondary plug may be retracted into a cavity in the housing of the primary plug. Like the plugs disclosed in the '271 Patent and the '178 Patent, the prongs of the primary plug are joined by a casing that rotates with the prongs to place the primary plug in the retracted state. However, neither the '460 Patent, the '807 Patent, nor the '381 Patent discloses a system suitable for retracting and extending all three prongs in a three-prong electrical plug connector. Furthermore, these patents do not disclose a simple way for a user to extend the retracted prongs.
A TeleAdapt press release dated Mar. 22, 2001 discusses a folding plug product in which a three prong foldable electrical plug connector folds into its housing along an axis of rotation in the middle of the plug body. The three prongs are joined by a portion of the housing. However, this type of plug body appears to occupy more space than a typical electrical plug connector, rather than save space.
U.K. Patent Application No. 9514143.8 (“the '143 UK Application”) and U.K. Patent Application No. 8901083.9 (“the '083 UK Application”) each describe a three-prong foldable electrical plug connector, whose prongs are pivotally retracted into recesses in a body of the plug. In the connector described in the '143 UK Application, a ball-and-spring mechanism is used to maintain each prong in an extended position. The '143 UK Application shows all three prongs fold down in the same direction; whereas, in the '083 Application, a third prong folds in a direction opposite to the direction in which the first two prongs fold. However, neither the '143 UK Application nor the '083 UK Application discloses a mechanism, whereby the user may retract all of the prongs simultaneously or by a single force or action, making the process of extending or retracting the prongs needlessly cumbersome.